For decades, the methods and apparatus used in warehouse storage have changed very little. FIG. 1A illustrates an exploded view of a standard wooden pallet 100 similar to those which are used in warehouse storage operations. The top half of the wooden pallet 100 is made up of parallel wooden deck boards 101. The deck boards rest on, and are secured to, three parallel stringer boards 105 which are aligned perpendicular to the deck boards. The outer stringer boards 105A, 105C are disposed along the outer edges of the deck boards, and the center stringer board 105B is disposed halfway between the outer stringer boards. Typically, the deck boards are secured to the stringer boards by nails or high-strength staples. The bottom half of the pallet is identically constructed of three parallel stringer boards 105D, 105E, 105F, secured to a plurality of lower deck boards 103. The top and bottom halves of the pallet are secured to each other by wooden spacer blocks 107 disposed along the stringer boards.
Within industry, the “width” of a wooden pallet is generally the length of the deck boards, and the “length” of a wooden pallet is generally the length of the stringer boards. Regardless of the number of spacer blocks 107 disposed along the stringer boards, a pallet is normally configured to receive the insertion of forklift blades according to the orientation of directional arrows FLB1. As used throughout this disclosure, this “insertion” side will be referred to as the “front” of the pallet. Because of the symmetry on most pallets the reader will appreciate that a forklift machine can similarly insert its forklift blades from the rear of the pallet. If three spacer blocks are evenly spaced along each stringer board, a forklift machine will also be able to insert its blades between the upper and lower portions of the pallet from the “side” of the pallet, as illustrated by directional arrows FLB2. Wooden pallets capable of receiving an insertion of forklift machine blades from only the front and back are typically known as “two-way” pallets. Wooden pallets that can also receive forklift blade insertion from the left and right sides are typically known as “four-way” pallets
FIG. 1B discloses the wooden pallet of FIG. 1A in an assembled state. In many pallets, the bottom half of pallet 100 if typically identical in design to the upper half, such that the pallet will function identically regardless of which side is facing up. A benefit of this design is that if one or more of the wooden deck boards 101 on one side of the pallet are damaged, a warehouse worker may flip the pallet such that the top side of the pallet comprises undamaged wooden deck boards more suitable for supporting various commodities and goods. The insertion slots 109A and 109B receive fork lift blades at the front and rear of the pallet, and, for four-way pallets, insertion slots 111A, 111B along the sides of the pallet can also receive fork lift blades.
In an alternative embodiment of prior art wooden pallets, “runners” (not shown) approximately the same height as wooden spacer blocks extend the length of the pallet in place of the stringer boards of FIG. 1A. Alternatively, runners may be used in conjunction with stringer boards, each runner being disposed between an upper stringer board and a corresponding lower stringer board in an assembled palette. Runners may have horizontally elongated mouse-hole type slots cut therein, providing “four way” access to a pallet by a fork lift machine.
FIG. 2 depicts a package of goods 201 affixed to a disposable pallet 203 which itself rests on a wooden pallet 100. The package 201 is wrapped with strapping bands 205 which are typically made from either steel or nylon. The strapping bands 205 may be tightened by a strapping machine (not shown) or a hand held tightening device (also not shown) and secured in a taut condition by a wire loop buckle 207 for nylon strapping bands or a metal crimp buckle (not shown) for steel strapping bands. In the embodiment of FIG. 2, the strapping bands 205 secure the package 201 to the disposable pallet 203. A disposable pallet 203 is typically made principally of cardboard, or a combination of cardboard and wood. A disposable pallet 203 is typically less expensive to fabricate than a wooden pallet 100. However, disposable pallets do not normally have insertion slots into which forklift machine blades may be inserted, and are not as rugged as wooden pallets. However, by using a disposable pallet 203 in conjunction with a typical wooden pallet 100, as shown in FIG. 2, the insertion slots 109A and 109B of the wooden pallet facilitate storage and retrieval of the wooden pallet, and any content stored thereon, by forklift machine 301 (FIG. 3). The disposable pallet 203 provides a stable and durable base for package 201. Depending upon the weight, height, and the general stability of a package, when a package with an integral disposable pallet is a placed on a wooden pallet, the package may be secured to the wooden pallet by means of strapping bands to provide additional stability when being moved by a forklift machine.
To initially position a package with a disposable pallet onto a wooden pallet, a variety of techniques are used by warehouse workers. For lighter packages, warehouse workers may tilt a package onto a back edge, slide a wooden pallet underneath it, and lower the package onto the wooden pallet. Because this process typically leaves the back edge of the package hanging off of the wooden pallet, warehouse workers will attempt to center the package on the wooden pallet by creeping the package toward the center of the wooden pallet, often standing on the wooden pallet during the process to prevent the wooden pallet from sliding away.
In embodiments wherein the package is too heavy for warehouse workers to tilt onto a back edge, or creep into a stable position in the center of a wooden pallet, a forklift machine may be used. Forklift machines typically have two parallel blades. Each blade has a vertical portion proximate forklift machine and a horizontal portion extending forward from the bottom of the vertical portion. Fork lift machine blades are typically formed from a continuous steel member such that the vertical portion and horizontal portion meet at a 90° bend at the bottom of the vertical portion of the forklift blades. The horizontal portion of a fork lift blade is about an inch and a half thick, depending on the size of the forklift machine and the weight limit for which it is designed. The horizontal portion of the blade is tapered at the distal end of the blade thereby allowing a skilled forklift driver to advance the tapered end of the blades underneath packages resting on the floor.
When a forklift machine is used to place a package onto a wooden pallet, the forklift driver typically lowers the distal ends (the tips) of the blades to the warehouse floor, with the blades either parallel to the floor, or tilted at a slight downward angle toward the tips. The forklift driver advances the forklift machine toward the package with the distal edge of the blades touching, or almost touching the floor, thereby sliding the blades underneath the package. The blades are then raised, lifting the package off the warehouse floor, allowing warehouse workers slide a wooden pallet underneath the package. The fork lift machine then lowers the package onto the wooden pallet. To allow the forklift machine blades to be withdrawn without pulling the package off of the wooden pallet, the forklift machine driver may tilt the distal ends of the forklift blades downward, thereby lowering the distal edge of the package onto the wooden pallet. As the weight of the package is distributed disproportionately along the back edge of the package, the forklift machine backs up, thereby withdrawing the blades so as to lower the bottom surface of the package out of the wooden pallet without dragging the package off of the wooden pallet. Because the positioning of a package onto a pallet is about one third art, one third science, and one third brute force, the technique described above is simply offered to be illustrative, and is not intended to limit the techniques that warehouse workers use to move large packages by fork lift.
It can be readily appreciated that the proper insertion of forklift machine blades to a desired depth under a package is usually dependent upon several factors. First, it is important that a warehouse floor be smooth and level so that the tapered (distal) ends of the forklift blades can slide underneath the package, rather than piercing the package. A second factor influencing the depth of penetration of fork lift blades under a package or disposable pallet is the angle of the forklift machine blades relative to the ground. To slide fork lift blades underneath a package or disposable pallet resting on the floor, the horizontal portion of the forklift blade is tilted “downward” slightly such that the distal end is the lowest portion of the horizontal section. According to the judgment of the forklift machine driver, this angle of downward tilt is typically between 1 degree and 15 degrees. It can be appreciated that, as a forklift blade advances beneath a package, the angle of tilt will be transmitted to the package itself, gradually lifting the proximal end of the package, thereby incurring progressively greater friction between the forklift blades and the bottom of the package as the forklift machine advances. Eventually, a package may begin to slide backwards from this force before the forklift machine blades have been inserted to a proper depth. To ensure proper depth of insertion, a third factor considered by a forklift machine driver is speed, acceleration and breaking. If the forklift machine is advancing too slowly, excess friction between the package in the blades may begin to push the package backwards before the forklift blades are properly seated underneath the package. If the forklift machine is advancing too quickly, the blades will slide under the disposable pallet until the face of the package impacts the vertical portions of the blades. The package is then driven backwards until the fork lift machine stops. If the forklift machine is advancing at an optimal rate, the horizontal portions of the blades will slide all the way underneath the package until the vertical portions of the forklift blades touch, or very nearly touch the forward face of the package.
It can be readily appreciated that while such techniques are appropriate for sliding the blades of a forklift machine underneath a package resting on a warehouse floor, they would be unworkable and even dangerous if used to retrieve packages stacked on top of each other, or stored on shelves. On the floor, a forklift machine can use the warehouse floor to adjust the height of the tips of the forklift blades before advancing toward a package. For retrieval from shelves, the proper height of the forklift blades can only be estimated. Forklift blades that were too high could penetrate a package, dent the contents stored within the package, or drive the package backward, possibly pushing it off the far end of the shelf. Forklift blades that are aligned to low can smash into a horizontal load beam along the forward edge of a shelf, either progressively damaging shelf, or even tipping over an entire shelf, creating a costly and dangerous situation. Because of these limitations, stacked storage techniques known in the prior art seldom use forklift machines to store a heavy package on a shelf unless the package is disposed on a wooden pallet.
FIG. 3 discloses a forklift machine 301 retrieving a package 201 from a storage shelf 305. The forklift machine has forklift blades 303 are raised to approximately the height of a wooden pallet 100 to which a package 201 is a secured. The package 201 is stored on the top shelf of a high stack storage shelf 305. Typically, retrieval is performed by raising the forklift blades to the level of the insertion slots 109A, 109B of wooden pallet 100 on which the palletized goods rest, and advancing the forklift machine so as to insert the forklift blades into the insertion slots. The pallet is raised when the blades are fully inserted.
Returning to FIG. 2, even when packages include an integral disposable pallet, the package 201 is often secured to a wooden pallet by strapping bands to improve stability and safety when moved via a fork lift machine. In securing a package in this manner, strapping bands are typically threaded through the cavity between a upper and lower deck boards. Strapping bands running widthwise between the upper and lower deck boards secure the package to the wooden pallet by wrapping around the outer stringer boards. Strapping bands running lengthwise between the upper and lower deck boards secure the package to help by wrapping around some or all of the deck boards.
To secure a large package to a pallet, the tensile force applied to each strapping band can be several hundred pounds. When a package is secured to a wooden pallet, the force transmitted by the strapping bands to the deck boards is often enough to pull the deck boards off of the stringer boards, or even crack the deck boards.
In addition to the damage caused to wooden pallets by strapping bands, forklift machines progressively destroy wooden pallets. A collision between the forklift blades 303 and the wooden spacer blocks 107 frequency occurs during blade insertion. Because forklift machines are generally quite powerful, a single such collision can loosen, dislodge, or even split a wooden spacer block. Additionally, a forklift machine often lacks sufficient room to approach a pallet head-on for direct insertion of forklift blades into the insertion slots 109A, 109B. To rotate a wooden pallet, a forklift machine driver will insert the tips of the forklift machine blades into the insertion slots 109A, 109B, turn the steering wheel of a forklift machine sharply, and backup, thereby forcing the forklift blades into the wooden spacers 107, exerting a lateral force sufficient to rotate a pallet. The heavier the load, the more force is required to rotate the pallet. Again, the force required to perform this maneuver takes its toll on wooden spacers, which are eventually loosened, dislodged, or destroyed. Additionally, hand pallet trucks typically have a pump action handle that hydraulically raises the lift-blades relative to the wheels, exerting thereby downward force against the wheels equal to the upward force necessary to raise the pallet. If the wheels are resting on a lower deck board, as the pallet is raised by the hydraulic cylinder, a deck board pinned underneath the wheel is ripped from the stringer boards, or split in two.
Damage to wooden pallets is an ongoing process in most warehouse environments. Because of this, a large warehouse may have a team of workers dedicated to the continual repair of pallets. Alternatively, a warehouse they may simply purchase an inflow of new pallets. Even when repaired, most pallets reach their repair limit, after which they are simply discarded, or disassembled and cannibalized for whatever usable wood might be left. This ongoing repairer and replacement of wooden pallets represents a significant expense for many companies.
Table 1 references the ten most common sizes of wooden pallets used in the United States, along with the industries that frequently use these respective sizes. Dimensions of Table 1 are in inches.
TABLE 1Grocery48 × 40Telecom, Paint42 × 40Drums48 × 48Cement40 × 48Chemical48 × 42Dairy40 × 40Automotive48 × 45Drums, Chemical44 × 44Beverage36 × 36Beverage, shingles, packaged paper48 × 36
Because these ten sizes represent only about sixty percent of the total number of pallets used in America, it can be readily appreciated that there is no “official” size for a pallet. Additionally, European nations and other metric regions add to the variety of pallet sizes, as illustrated in Table 2. Dimensions of Table 2 are in centimeters.
TABLE 2⅛ Euro40 × 30¼ Euro60 × 40½ Euro80 × 60Euro ISO 1 80 × 120Euro ISO 2100 × 120114 × 114110 × 110
Because of the expense in maintaining and replacing wooden pallets, industry has sought alternative solutions. Disposable cardboard pallets have been fitted with “feet” configured to raise a package a sufficient distance from the ground to allow insertion of forklift blades beneath the package. Feet integrally coupled to a carton or a disposable pallet are often cylindrical in shape, or may define a conical frustum. They are commonly in the range of six inches in diameter, and may be formed from molded plastic, with flanges extending horizontally from the upper limit of the cylinder. Corrugated cardboard layers above and below these flanges secure the feet to the carton or disposable pallet. The addition of feet to a disposable pallet however, significantly increases the cost of a carton or disposable pallet. Moreover, because a disposable pallet lacks the rigidity and strength of a wooden pallet, such designs cannot fully replace the functionality of traditional wooden pallets, and sometimes function as a limitation.
There remains therefore need for a method and apparatus for eliminating or reducing the ongoing expenses associated with procurement, repair and replacement of wooden pallets while retaining many of the advantages of wooden pallets.